For a little while on Thursday, United Airlines was giving away airplane tickets for free, or close to it.

Passengers reported buying tickets for $5 to $10 before United shut down the bookings on its website and phone centers to prevent more tickets from being sold or given away.

The airline said it accidentally filed some fares for $0. Airport charges might have resulted in a small cost seen by some passengers.

Bob Stokas, of the Chicago suburb Oak Lawn, was one of the lucky ones who was perusing the site for fares at the right time. He was searching for a round-trip ticket to LA next June to watch the Sox -- and expecting to pay up to $400 for each ticket -- when noticed the bargain-basement fares.

"When I scrolled down past the non-stop fares, when I got to the connecting flights, the flights to and from Los Angeles per person was $10," Stokas said. "That was a shock and a surprise, and I was like, 'I've got to book this flight right now before they rescind their offer of $10 for this flight.'"

Stokas ended up buying tickets for his two kids and his parents -- a total of six tickets for $60. By the time he started trying to buy tickets to Roanoke, Va., for this weekend, the site shut down.

So is he worried that United might invalidate the cheap tickets?

"My opinion is that United, from a PR perspective, needs to honor the tickets and honor the contract that we established for $10 each way," Stokas says. "I believe the contract was in good faith -- we're good customers of United, been flying them for years."

The website was accepting reservations again around 2:45 p.m. Central time.

Such fare mistakes have happened before, often when an airline dropped a digit when entering fares into its computer system.

That may be what happened here. United Continental Holdings Inc. spokeswoman Megan McCarthy said the mistake was due to an error in filing the fares, not a problem with the website. She said United doesn't yet know how many tickets were sold at the unusually low prices.

Airline officials are thinking about honoring the tickets but a final decision hasn't been make.